Geochemistry of surface sediments in the southwestern East/Japan Sea

Cha, Hyunju; Choi, Man-Sik; Lee, Chang-Bok; Shin, Dong-Hyeok

doi:10.1016/j.jseaes.2006.04.009

Cited by 60 publications

(30 citation statements)

References 28 publications

(36 reference statements)

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“…Compared with the five modern geochemical sub-environments of the SW Japan Sea, the Guryul sediments resemble the inner shelf (type IV) and coastal and upper slope (type III) clusters, although the sediments are very variable, in their relatively low Mg, Ti, Fe, relatively high Cr, variable Zn, Co, and low Fe/Al ratios (Cha et al, 2007).…”

Section: Provenance and Climate Summarymentioning

confidence: 95%

Palaeoenvironments and elemental geochemistry across the marine Permo‐Triassic boundary section, Guryul Ravine (Kashmir, India) and a comparison with other North Indian passive margin sections

Brookfield

Stebbins

Williams

et al. 2019

The Depositional Record

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The Guryul Permian-Triassic sediments were deposited on a passive margin in a partially enclosed basin, at a latitude of about 45°S along the southern margin of the Neotethys Ocean. The closest modern analogy is the Japan Sea rotated into a southern hemisphere orientation. Guryul element variations are subdued, mostly lithological, and take place across the change from the dominantly sandy shallow-water Permian Zewan Formation into the dominantly shaly deeper-water latest Permian-Triassic Khunamuh Formation, and not at the palaeontological Permian-Triassic boundary.The overall geochemistry of the Guryul sediments is very similar to that of the Ulleung Basin in the Japan Sea, where the sediments are 40%-60% eolian from loess and redeposited loess in the North China Basin. The overall Guryul geochemistry indicates that the sediments were derived from dominantly silica-rich continental rather than silica-poor sources although with some more silica-poor inputs at times. Element ratios suggest increasing aridity and wind abrasion across the Permian-Triassic boundary. Various geochemical redox proxies suggest mainly oxic depositional conditions, with episodes of anoxia, but with little systematic variation across the extinction boundary. Productivity proxies suggest a slight decrease across the Permian-Triassic boundary, and at least one more decreased interval in the Early Triassic. The similar geochemistry of other localities indicate that the Guryul geochemical changes are regional in extent and representative of the North Indian Permian-Triassic passive margin. The lack of consistent element geochemical changes across the boundary accompanied by significant C, S, and other isotopic changes suggests that atmospheric and oceanic chemistry rather than physical changes, such as provenance, climate and sea-level changes, drove the Permian-Triassic environmental changes and extinctions at least on the mid-latitude Tethyan shelf of northern India. K E Y W O R D S Extinction, geochemistry, Kashmir, Permian-Triassic 76 | BROOKFIELD Et aL. F I G U R E 1 Late Permian palaeogeography (courtesy of Chris Scotese): Early Triassic "dead zone" from Sun et al. (2012); Winds from Kiehl and Shields (2005). Locations of cited Permo-Triassic boundary section in open circles with names in bold face 78 | BROOKFIELD Et aL. F I G U R E 8 Biostratigraphy of the Guryul Permian-Triassic boundary section showing stratigraphic range of fossils and number of species in each subdivision (data from Nakazawa et al., 1975). Bryo -bryozoans. Gastr -gastropods. Note that there is little extinction at the Zewan-Khunamuh Formation boundary and the main extinction (and new species appearance) is at the FAD of Hindeodus parvus, and the first inferred anoxic level marked by pyrite framboids.

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Section: Provenance and Climate Summarymentioning

confidence: 95%

Palaeoenvironments and elemental geochemistry across the marine Permo‐Triassic boundary section, Guryul Ravine (Kashmir, India) and a comparison with other North Indian passive margin sections

Brookfield

Stebbins

Williams

et al. 2019

The Depositional Record

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“…Organic carbon flux observed by a sediment trap at 1020 m was ~9 g C m -2 yr -1 is comparable to that of a Chilean upwelling region where organic carbon accumulation rates were ~3 g C m -2 yr -1 and is unusually high for deep sediments (Lee et al 2008). In addition, accumulating sedimentary organic carbon contents reach up to ~4% (Cha et al 2007;Lee et al 2010). As inferred from extremely high organic matter inputs to the bottom layer, a 'micro reducing environment̓ may be formed in the bottom layer (Wolgast et al 1998), enabling an upward extension of denitrifying bacterial activity from the sediments to the bottom waters above.…”

Section: Extended Benthic Denitrification To Bottom Waters Vs 'Aerobmentioning

confidence: 99%

“…As inferred from extremely high organic matter inputs to the bottom layer, a 'micro reducing environment̓ may be formed in the bottom layer (Wolgast et al 1998), enabling an upward extension of denitrifying bacterial activity from the sediments to the bottom waters above. Recent increases in atmospheric nitrogen deposition flux to the EJS (Kim et al 2011), warming of the water column (Gamo et al 2001;Kim et al 2001Kim et al , 2004Min and Kim 2006), oxygen content decreases (Kim and Kim 1996;Chen et al 1999;Gamo 1999;Kang et al 2004), and high deposition rates of organic matter (Cha et al 2007;Tishchenko et al 2007;Lee et al 2008Lee et al , 2010Hyun et al 2010) might have created a favorable environment for denitrification in the bottom layer at the two basins in the EJS in recent years.…”

Section: Extended Benthic Denitrification To Bottom Waters Vs 'Aerobmentioning

confidence: 99%

Deep Nitrate Deficit Observed in the Highly Oxygenated East/Japan Sea and Its Possible Cause

Kim¹,

Min²,

Lee³

2012

Terr. Atmos. Ocean. Sci.

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We present evidence of denitrification on the continental slopes of the Ulleung Basin (UB) and the Eastern Japan Basin (EJB) near the Tatar Strait (TtS) in the East/Japan Sea (EJS), despite its high water column dissolved oxygen concentrations. Some nutrient concentration data deviate significantly from the fitted regression line of nitrate (N) vs. phosphate (P) in deep waters, indicating a loss of nitrate in the region. The EJS has a lower N/P ratio (ca. 12.4 below 300 dbar) than a traditional Redfield ratio (16). The N/P ratio and oxygen concentration are substantially lower at several locations whose depths are close to the sediment-water interface, near TtS (500 -1100 dbar) and in UB (1100 -2200 dbar). The decreased nitrate concentration is smaller than the expected nitrate level (a low N/P ratio of < 12.4), and a secondary nitrite peak near the bottom of these two regions: taken collectively, both indicate the presence of denitrification in the bottom layer. It is speculated that active re-mineralization and denitrification may occur simultaneously along the rich organic matter bottom layer on the slope environment. Denitrification rates are estimated at ~3 -33 μmol N m -2 d -1 . Current estimates do not support the previous idea of basin-wide denitrification in EJS, although the N/P ratio is low like in other hypoxic/anoxic seas. A better understanding of the denitrification process is necessary for predicting future changes of nitrogen cycle in the well-oxygenated EJS considering the decadal-scale physical and biogeochemical changes that have occurred.

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“…The Ulleung Basin is semi-enclosed by the continental margin of the Korean Peninsula to the west and by the rugged Korea Plateau to the north. In the east and south, the basin is bounded by the gentle slope and broad shelf of the Japanese Arc and the Oki Bank (Bahk et al, 2000;Cha et al, 2007). The water depth of the basin ranges from 1500 to 2300 m and gradually deepens toward the Ulleung Interplain Gap (to a maximum of 2400e3200 m of water depth; Lee and Kim, 2002).…”

Section: Sites Of Interestmentioning

confidence: 99%

Geotechnical properties of deep oceanic sediments recovered from the hydrate occurrence regions in the Ulleung Basin, East Sea, offshore Korea

Kwon

Lee

Cho

et al. 2011

Marine and Petroleum Geology

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Geochemistry of surface sediments in the southwestern East/Japan Sea

Cited by 60 publications

References 28 publications

Palaeoenvironments and elemental geochemistry across the marine Permo‐Triassic boundary section, Guryul Ravine (Kashmir, India) and a comparison with other North Indian passive margin sections

Palaeoenvironments and elemental geochemistry across the marine Permo‐Triassic boundary section, Guryul Ravine (Kashmir, India) and a comparison with other North Indian passive margin sections

Deep Nitrate Deficit Observed in the Highly Oxygenated East/Japan Sea and Its Possible Cause

Geotechnical properties of deep oceanic sediments recovered from the hydrate occurrence regions in the Ulleung Basin, East Sea, offshore Korea

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